不同类型地膜覆盖对玉米农田土壤酶活性的影响

为探讨不同类型地膜覆盖下农田土壤酶活性变化特征，试验设置普通地膜覆盖（P）、渗水地膜覆盖（SS）、生物降解地膜覆盖（SW）和光降解地膜覆盖（G）4种不同类型地膜覆盖模式，以露地不铺膜覆盖（CK）为对照，研究不同类型地膜覆盖方式对玉米农田土壤酶活性的影响。结果表明：SS、G、SW和P 4种覆膜处理下的碱性磷酸酶和硝酸还原酶在各个生育期内都较CK高，而覆膜之后的脲酶、过氧化氢酶和亚硝酸还原酶则较CK有所降低；大喇叭口期的土壤脲酶活性最高，不同处理间表现为CK > G > SW > SS > P；收获期的土壤碱性磷酸酶活性最高，SS、SW、P和G处理在0~20 cm土层较CK增幅分别为16.17%、18.97%、16.34%和14.56%，土壤硝酸还原酶活性也是收获期最高，SS、SW、P和G处理在0~20 cm土层分别较CK高68.57%、42.86%、42.86%和25.71%；土壤碱性磷酸酶与硝酸还原酶活性的变化均与土壤呼吸率和玉米产量呈极显著正相关（P<0.01），各个生育期的土壤水热和施肥状况不同也会引起土壤酶活性的相应变化。其中，SW和SS处理在玉米生育前期的保温保墒作用最明显，产量最高，相应的碱性磷酸酶和硝酸还原酶活性也最高。因此，生物降解地膜由于其降解特性能达到缓解农田残膜污染的效果，在未来可替代普通地膜推荐应用到旱地玉米中。

Effects of different plastic film mulching on soil enzyme activity in maize farmland

In order to explore the characteristics of soil enzyme activities under different types of plastic film mulching, we set up four different types of plastic film mulching models at Dongyang experimental base of Agricultural Sciences Academy in Shanxi Province in 2016, including common plastic film mulching(P), water-permeable plastic mulching film(SS), biodegradable plastic film mulching(SW), light degradation mulching(G), uncovered film covering in open field(CK) was used as control. The results showed that alkaline phosphatase and nitrate reductase under four kinds of coating treatments were higher than CK in all growth stages, while urease, catalase, and nitrite reductase under plastic film were lower than CK; Soil urease activity was highest in flare opening stage, with CK > G > SW > SS > P; Alkaline phosphatase activity was highest during harvest, SS, SW, P, and G treatments at 0~20 cm soil were 16.17%, 18.97%, 16.34%, and 14.56% highter than CK. The activity of nitrate reductase at 0~20 cm soil of SS, SW, P, and G treatments were 68.57%, 42.86%, 42.86%, and 25.71% higher than that of CK; Combining other factors such as maize yield, we found that the changes of soil alkaline phosphatase activity and nitrate reductase activity were highly significant positively correlated with soil respiration rate and maize yield(P<0.01), Soil hydrothermal and fertilization conditions at different growth stages caused corresponding changes in soil enzyme activity. Among them, SW and SS treatments had obviously effects on the temperature raising and water saving of maize soil during the early growth period, they also had the highest yield, with the highest corresponding alkaline phosphatase activity and nitrate reductase activity, and SW had considerable degradation performance. Therefore, biodegradable plastic film in the future can be used as an alternatives of common mulch film applied to dry farmland, at the same time, it can achieve the effect of relieving farmland residual film pollution.